Generating Retinal Injury Models in Xenopus Tadpoles

Summary

We have developed several protocols to induce retinal damage or retinal degeneration in Xenopus laevis tadpoles. These models offer the possibility of studying retinal regeneration mechanisms.

Abstract

Retinal neurodegenerative diseases are the leading causes of blindness. Among numerous therapeutic strategies being explored, stimulating self-repair recently emerged as particularly appealing. A cellular source of interest for retinal repair is the Müller glial cell, which harbors stem cell potential and an extraordinary regenerative capacity in anamniotes. This potential is, however, very limited in mammals. Studying the molecular mechanisms underlying retinal regeneration in animal models with regenerative capabilities should provide insights into how to unlock the latent ability of mammalian Müller cells to regenerate the retina. This is a key step for the development of therapeutic strategies in regenerative medicine. To this aim, we developed several retinal injury paradigms in Xenopus: a mechanical retinal injury, a transgenic line allowing for nitroreductase-mediated photoreceptor conditional ablation, a retinitis pigmentosa model based on CRISPR/Cas9-mediated rhodopsin knockout, and a cytotoxic model driven by intraocular CoCl₂ injections. Highlighting their advantages and disadvantages, we describe here this series of protocols that generate various degenerative conditions and allow the study of retinal regeneration in Xenopus.

Introduction

Millions of people worldwide are afflicted with various retinal degenerative diseases leading to blindness, such as retinitis pigmentosa, diabetic retinopathy, or age-related macular degeneration (AMD). To date, these conditions remain largely untreatable. Current therapeutic approaches under evaluation include gene therapy, cell or tissue transplantations, neuroprotective treatments, optogenetics, and prosthetic devices. Another emerging strategy is based on self-regeneration through the activation of endogenous cells with stem cell potential. Müller glial cells, the major glial cell type of the retina, are among cellular sources of interest in this context. Upo....

Protocol

Animal care and experimentation were conducted in accordance with institutional guidelines, under the institutional license A91272108. The study protocols were approved by the institutional animal care committee CEEA #59 and received authorization by the Direction Départementale de la Protection des Populations under the reference number APAFIS #32589-2021072719047904 v4 and APAFIS #21474-2019071210549691 v2. See the Table of Materials for details related to all materials, instruments, and reagents .......

Discussion

Advantages and disadvantages of various retinal injury paradigms in Xenopus tadpoles

Mechanical retinal injury
Various surgical injuries of the neural retina have been developed in Xenopus tadpoles. The neural retina may either be entirely removed^15,16 or only partly excised^16,17. The mechanical injury presented here doe.......

Materials

Name	Company	Catalog Number	Comments
1,2-Propanediol (propylène glycol)	Sigma-Aldrich	398039
Absolute ethanol ≥99.8%	VWR chemicals	20821-365
Anti-Cleaved Caspase 3 antibody (rabbit)	Cell signaling	9661S	Dilution 1/300
Anti-GFP antibody (chicken)	Aveslabs	GFP-1020	Dilution 1/500
Anti-M-Opsin antibody (rabbit)	Sigma-Aldrich	AB5405	Dilution 1/500
Anti-mouse secondary antibody, Alexa Fluor 594 (goat)	Invitrogen Thermo Scientific	A11005	Dilution 1/1,000
Anti-Otx2 antibody (rabbit)	Abcam	Ab183951	Dilution 1/100
Anti-rabbit secondary antibody, Alexa Fluor 488 (goat)	Invitrogen Thermo Scientific	A11008	Dilution 1/1,000
Anti-rabbit secondary antibody, Alexa Fluor 594 (goat)	Invitrogen Thermo Scientific	A11012	Dilution 1/1,000
Anti-Recoverin antibody (rabbit)	Sigma-Aldrich	AB5585	Dilution 1/500
Anti-Rhodopsin antibody (mouse)	Sigma-Aldrich	MABN15	Dilution 1/1,000
Anti-S-Opsin antibody (rabbit)	Sigma-Aldrich	AB5407	Dilution 1/500
Apoptotis detection kit (Dead end fluorimetric TUNEL system)	Promega	G3250
Benzocaine	Sigma-Aldrich	E1501	Stock solution 10%
bisBenzimide H 33258 (Hoechst)	Sigma-Aldrich	B2883	Stock solution 10 mg/mL
Butanol-1 ≥99.5%	VWR chemicals	20810.298
Calcium chloride dihydrate (CaCl2, 2H2O)	Sigma-Aldrich (Supelco)	1.02382	Use at 0.1 M
Cas9 (EnGen Spy Cas9 NLS)	New England Biolabs	M0646T
Clark Capillary Glass model GC100TF-10	Warner Instruments (Harvard Apparatus)	30-0038
Cobalt(II) chloride hexahydrate (CoCl2, 6H2O)	Sigma-Aldrich	C8661	Stock solution 100 mM
Coverslip 24 x 60 mm	VWR	631-1575
Dako REAL ab diluent	Agilent	S202230-2
Dimethyl sulfoxide (DMSO)	Sigma-Aldrich	D8418
Electronic Rotary Microtome	Thermo Scientific	Microm HM 340E
Eosin 1% aqueous	RAL Diagnostics	312740
Fluorescein lysine dextran	Invitrogen Thermo Scientific	D1822
Fluorescent stereomicroscope	Olympus	SZX 200
Gentamycin	Euromedex	EU0410-B
Glycerin albumin acc. Mallory	Diapath	E0012	Use at 3% in water
Hematoxylin (Mayer's Hemalun)	RAL Diagnostics	320550
HEPES potassium salt	Sigma-Aldrich	H0527
Human chorionic gonadotropin hormone	MSD Animal Health	Chorulon 1500
Hydrochloric acid fuming, 37% (HCl)	Sigma-Aldrich (SAFC)	1.00314
L-Cysteine hydrochloride monohydrate	Sigma-Aldrich	C7880	Use at 2% in 0.1x MBS (pH 7.8 - 8.0)
Magnesium Sulfate Heptahydrate (MgSO4, 7H2O)	Sigma-Aldrich (Supelco)	1.05886
Metronidazole	Sigma-Aldrich (Supelco)	M3761	Use at 10 mM
Microloader tips	Eppendorf	5242956003
Micropipette puller (P-97 Flaming/Brown)	Sutter Instrument Co.	Model P-97	Program : Heat 700 / Pull 100 / Vel 75 / Time 90 / Unlocked p = 500
Mounting medium to preserve fluorescence, FluorSave Reagent	Millipore	345789
Mounting medium, Eukitt	Chem-Lab	CL04.0503.0500
MX35 Ultra Microtome blade	Epredia	3053835
Needle Agani 25 G x 5/8''	Terumo	AN*2516R1
Nickel Plated Pin Holder	Fine Science Tools	26016-12
Nylon filtration tissue (sifting fabric) NITEX, mesh opening 1,000 µm	Sefar	06-1000/44
Paraffin histowax without DMSO	Histolab	00403
Paraformaldehyde solution (32%)	Electron Microscopy Sciences	EM-15714-S	Use at 4% in 1x PBS pH 7.4
Peel-A-Way Disposable Embedding Molds	Epredia	2219
Pestle	VWR	431-0094
Petri Dish 100 mm	Corning Gosselin	SB93-101
Petri Dish 55 mm	Corning Gosselin	BP53-06
Phosphate Buffer Saline Solution (PBS) 10x	Euromedex	ET330-A
PicoSpritzer Microinjection system	Parker Instrumentation Products	PicoSpritzer III
Pins	Fine Science Tools	26002-20
Polysucrose (Ficoll PM 400 )	Sigma-Aldrich	F4375	Use at 3% in 0.1x MBS
Potassium chloride (KCl)	Sigma-Aldrich	P3911
Powdered fry food : sera Micron Nature	sera	45475 (00720)
Scissors dissection	Fine Science Tools	14090-09
Slide Superfrost	KNITTEL Glass	VS11171076FKA
Slide warmer	Kunz instruments	HP-3
Sodium chloride (NaCl)	Sigma-Aldrich	S7653
Sodium citrate trisodium salt dihydrate (C6H5Na3O7, 2H2O)	VWR chemicals	27833.294
Sodium hydrogen carbonate (NaHCO3)	Sigma-Aldrich (Supelco)	1.06329
Sodium hydroxide 30% aqueous solution (NaOH)	VWR chemicals	28217-292
Stereomicroscope	Zeiss	Stemi 2000
Syringes Omnifix-F Solo Single-use Syringes 1 mL	B-BRAUN	9161406V
trans-activating crRNA (tracrRNA)	Integrated DNA Technologies	1072533
Triton X-100	Sigma-Aldrich	X-100
Tween-20	Sigma-Aldrich	P9416
X-Cite 200DC Fluorescence Illuminator	X-Cite	200DC
Xylene ≥98.5%	VWR chemicals	28975-325